Tall oil rosin of low sulfur content

ABSTRACT

DISCLOSED IS A PROCESS FOR REMOVING SULFUR COMPOUND IMPURITIES FROM TALL OIL ROSIN BY DISSOLVING TALL OIL ROSIN IN A SOLVENT FOLLOWED BY CRYSTALLIZATION OF THE ROSIN COMPONENT OF THE RESULTING SOLUTION.

United States Patent Oihce Int. Cl. C09f 1/02 US. Cl. 26097.7 6 ClaimsABSTRACT OF THE DISCLOSURE Disclosed is a process for removing sulfurcompound impurities from tall oil rosin by dissolving tall oil rosin ina solvent followed by crystallization of the rosin component of theresulting solution.

This invention relates to tall oil rosin containing relatively smallamounts of sulfur compound impurities and tothe method of obtainingsame.

Tall oil, a by-product recovered from pine wood black liquor of thesulfate paper process, is comprised of rosin acids, fatty acids, certainamounts of unsaponifiable material, and trace amounts ofsulfur-containing compounds. A representative tall oil rosin is onecomprised of, by weight, about 43% rosin acids (also referred to in theart as resin acids), about 41% fatty acids, about 16% unsaponifiablematerial and trace amounts of sulfur-containing compounds. Fractionaldistillation of tall oil yields a fraction rich in fatty acids, and afraction rich in rosin acids. The fraction rich in rosin acids is oftenreferred to in the art as tall oil rosin, and will contain small amountsof fatty acids and trace amounts of sulfur-containing compounds. Furtherrefinement of the tall oil rosin by distillation will lower the fattyacid content; however, the content of sulfur-containing compounds willremain substantially the same. The amount of sulfur present in thesulfur-containing compounds will usually be, by weight, at least about300 parts per million (p.p.m.) parts of tall oil rosin and higher. Thepresence of such amounts of sulfur renders the attempted hydrogenationof tall oil rosin uneconomical in that the sulfur poisons hydrogenationcatalysts, such as the noble metals, and renders them ineffective fortheir intended purpose.

Broadly, in accordance with this invention, there is provided a methodof obtaining tall oil rosin having a content of sulfur of about 100p.p.m. and less. It is understood that the sulfur is chemically combinedand not in elemental form.

The tall oil rosin employed in carrying out this invention will becomprised of fatty acids and sulfur-containing compounds, the amount ofsulfur present therein being from about 300 to about 600 parts permillion (p.p.m.) parts of tall oil rosin. The fatty acids content willbe less than about 10% by weight.

-In carrying out this invention, a solution is prepared by dissolving,by weight, from about 25 parts to about 67 parts of the tall oil rosinin about 75 parts to about 33 parts of a polar solvent. If required, thesolvent can be heated to accomplish substantially complete dissolutionof the tall oil rosin. The solution is subsequently cooled at least to atemperature at which the rosin acids will crystallize out.Crystallization is permitted to continue until the desired amount ofrosin acids has precipitated. The crystals can be recovered in anyconvenient Patented Apr. 11, 1972 manner as by decantation,centrifugation, filtration, or the like. The recovered crystals can bewashed to remove adhering impurities, if desired. Polar solvents, suchas those specifically disclosed herein, are recommended for the washingstep.

The polar solvent employed will be liquid under room temperatureconditions. Polar solvents that are liquid at temperatures as low asabout -40 C. can be satisfactorily employed. Suitable polar solvents foruse in carrying out this invention include acetone, methyl ethyl ketone,ethyl acetate, ethyl alcohol, methyl isobutyl ketone, isopropyl alcohol,diethylene glycol diethyl ether (diethyl Carbitol), diethylene glycoldimethyl ether (dimethyl Carbitol), and Z-methoxyethanol (methylCellosolve). Mixtures of two or more polar solvents can be employed ifdesired.

The following examples are illustrative of this invention. All parts andpercentages are by weight unless otherwise specified.

EXAMPLE 1 Tall oil rosin, 100 parts, having a fatty acid content ofabout 4% and containing sulfur-containing compounds, the amount ofsulfur present therein being about 550 parts per million (p.p.m.) partsof tall oil rosin is dissolved in an excess amount of acetone which hasbeen heated to its boiling point (about 565 C.) and the acetonedistilled off until there is provided a solution having a solids contentof about 50% The solution is cooled to a temperature of about 24 C. withconstant stirring and crystals are formed. The crystals are recovered byfiltration. The recovered crystals are washed with about 32 parts ofcold acetone (about 0 C.) and then again washed with about 32 parts ofcold acetone (about 0 C.). The Washed crystals are placed in an ovenmaintained at a temperature of about C. and dried. About 41.5 parts oftall oil rosin crystals are obtained which still contain trace amountsof sulfur-containing compounds; however, the amount thereof has beenreduced substantially. The amount of sulfur has been reduced from 550p.p.m. to 25 p.p.m.

EXAMPLE 2 Example 1 is repeated with the exception that the solution iscooled to 0 C. instead of 24 C. About 54.5 parts of tall oil rosincrystals are obtained which contain about p.p.m. sulfur.

EXAMPLE 3 Example 1 is repeated with the exception that the solution iscooled to a temperature of about -l7 C. instead of 24 C. About 62.2parts of crystals are obtained which contain about 60 p.p.m. sulfur.

EXAMPLE 4 Example 1 is repeated with the exception that ethyl acetate isemployed in place of the acetone of Example 1 and the resulting solutionis cooled to a temperature of about -17 C. instead of 24 C. About 63.1parts of crystals are obtained which contain about p.p.m. sulfur.

EXAMPLE 5 Example 1 is repeated with the exception that methyl ethylketone is employed in place of acetone. About 28.7 parts of crystals areobtained which contain about 50 p.p.m. sulfur.

The examples set forth in Table I below are in further illustration ofthis invention. Parts and percentages are by weight. In the Table Iexamples, the tall oil rosin employed has an acid number of 177.5 and iscomprised of,

4 of an organic polar solvent to provide a solution, (b) cooling thesolution at least to a temperature at which crystals of rosin acid form,and (c) recovering the crystals of rosin acid.

by weight, about 91.4% rosin acids; about 4.2% by weight 5 2. The methodof claim 1 wherein the polar solvent fatty acids, and trace amounts ofsulfur-containing comemployed is selected from the group consisting ofacetone, pounds, the amount of sulfur present therein being about methylethyl ketone, ethyl acetate, ethyl alcohol, methyl 520 p.p.m. isobutylketone, isopropyl alcohol, diethylene glycol di- TABLE 1 PercentCrystalsolids lization in tempera- Example Parts, Rosin soluture,Crystals Sulfur Number Solvent solvent (parts) tion 0. (parts) (p.p.m.)Remarks 6 Mehtyl ethyl ketone... 100 100 50 25 28.7 60 Crystals washedwith about parts of cold solvent (0 0.). 7.. Ethyl alcohol.. 100 100 5033.9 64 Do. 8.. Ethyl acetate. 100 100 50 25 29. 5 72 Do. 9.. Acetone100 100 50 25 33.0 40 Do. 10. ..do 200 200 50 0-3 100.0 52 Washed twicewith 32 parts solvent. 11 Methyl ethyl kctone 200 200 50 0-3 79.9 72 Do.12- alcohol 200 200 50 0-3 94. 5 76 D0. 13. e 100 200 66. 6 0-3 118.0 28Do. 14. Methyl ethyl keto 100 200 66. 6 03 103. o 24 Do. 15. Ethylalcohol 100 200 66. 6 0-3 113. 3 48 Do. 16- Ethyl acetate 100 200 66.60-3 115.6 24 Do. 17... Acetone 100 200 66. 6 25 100.8 56 Washed withabout 120 parts aeotonltl'llc. 1s... Ethyl alcohol 100 200 66.6 25 101.352 Do. 19--. Ethyl acetate 300 600 66.6 0-3 343.0 80 watslllleil thtretetimes with about 18 parts of B 2.08 a e. 20 Acetone 300 600 66.6 03386.0 100 Wasbbd three times with about 65 parts cold (0 C.) solvent.

The above examples illustrate a single crystallization ethyl ether,diethylene glycol dimethyl ether, Z-methoxystep. The sulfur content ofthe recovered crystals can be ethanol, and mixtures of two or more.further reduced if desired by repeating the crystallization 3. Themethod of claim 1 wherein the recovered crystals procedure using thesame or different solvent. The followare washed in an organic polarsolvent and subsequently ing example is illustrative of arecrystallization. dried.

EXAMPLE 21 4. The method of clalm 2 whereln the recovered crystals arewashed 1n an organic polar solvent and subse- About 50 parts of thecrystals of Example 1 are dlsquently dried. solved in 50 parts ofacetone to provide a solution having 5 Th h d of l i 1 h i h steps (b),a 50% solids content. The solution is cooled to about 25 nd r repeated tleast once. C. and crystals are formed. The crystals, about 25 parts, 6Th th d f 1 i 2 h r in th steps (b), are recovered by filtration andwashed twice with 10 d are repeated t l t once, parts of acetone (at 0C.). The washed crystals contain from about 5 to 10 p.p.m. combinedsulfur. References Cited rgflfiaiii lfi f $333231?iilfii iificifir filiit: UNITED STATES PATENTS tall oil rosin of this invention can behydrogenated g g 11/1950 Chistendon 26O 97-7 economically. Thehydrogenated product can be used in 547,20 4/1951 Hasselstrom themanufacture of adhesives 2,565,484 8/1951 Dunlap et al. 260--97.7 It isto be understood that the above description and 3,489,740 1/1970 choletet 260 97-7 examples are illustrative of this invention and not inlimita- OTHER REFERENCES tion thereof. 6; What I claim and desire toprotect by Letters Patent is: gg g g fg' and Chemlcal Engmeermg 1. Amethod for producing tall oil rosin containing less n 11 than about 10%by weight of tall oil fatty acids and having Hams Encyclopedla 0fchemcal Technlgy 1953 p. 781. a content of sulfur not in excess of about100 parts per million parts of tall oi l rosin which consistsessentially of DONALD CZAJA, Primary Examiner (a) dlSSOlVlIlg, byweight, from about 25 parts to about 67 parts of tall oil rosincontaining less than about 10% W. E. PARKER, Assistant Examiner byweight of tall oil fatty acids and sulfur-containing compounds, theamount of sulfur present therein being from about 300 to 600 parts permillion parts of tall oil rosin in about parts by weight to about 33parts by weight 0

